These text blocks are a nice way to call attention to the high-level phrases in a text hierarchy. As shown in the series example, they can easily be used as tracker pages within the presentation as well. There are two versions of these text blocks and each has two variations. One for use with light backgrounds and one for use with dark backgrounds. The variations (like the series thumbnail) are to illustrate that this design can be sued throughout the presentation as a design element as well. There is a trick to sizing these so that they appear consistent, so you'll want to review the series tutorial.